In circuit protection design, the problem of leakage current through varistors is a difficult challenge that engineers often encounter. As a type of voltage limiting protective device, varistors operate normally in a high resistance state with only microampere leakage current. However, when the problem of leakage current through varistors occurs, it not only increases the power consumption of the equipment, but may also cause circuit misoperation and even thermal breakdown failure. Taking the 10D561K model as an example, under 0.75 times the varistor voltage, the normal leakage current should be less than 50 μ A. Once it exceeds 100 μ A, attention should be paid to the risk of parameter drift. Therefore, effectively monitoring and solving the problem of leakage current in varistors is crucial for ensuring long-term stable operation of the circuit.
There are various reasons for the problem of leakage current in varistors. From an internal perspective, when zinc oxide varistors are subjected to voltage stress for a long time, the grain boundary potential barrier gradually decreases, resulting in leakage current increasing from microamperes to milliamps. From an external perspective, inadequate control of production processes can also lead to significant leakage current issues in varistors. For example, a case study has shown that a certain type of varistor, due to impurities in the solder flux on the packaging surface, undergoes a chemical reaction at high temperatures during reflow soldering, resulting in the migration of ZnO particles and an abnormal increase in leakage current. In addition, repeated exposure to surge impacts can accelerate the aging of varistors, causing their varistor voltage to become lower and lower, leading to the problem of large leakage current through varistors.
To address the issue of large leakage current in varistors, in addition to selecting and retaining appropriate margins during the design phase, choosing high-quality and highly reliable varistor products is the fundamental solution. As a professional manufacturer of circuit protection components, Yuanlin Electronics has been deeply involved in the field of varistors for many years. From chip research and development to process management, we strictly follow German process standards, and our products have passed international safety certifications such as UL, VDE, TUV, etc. Choosing Yuanlin Electronics not only effectively avoids the problem of leakage current in varistors, but also provides a durable and reliable circuit protection solution for your products.
